Device for coupling pipe sections

ABSTRACT

A device for coupling two pipe sections comprises a clamping band of U-shaped cross-section with two inwardly directed flanges for encompassing end beads of the pipe sections which are to be coupled. The ends of the clamping band have cylindrical pockets each accommodating a cylindrical element which is rotatable about its own axis in the pocket. The clamping band is clamped by means of a threaded screw which is passed through an unthreaded hole in one cylindrical element and unthreaded holes in the ends of the clamping band, whereupon the screw is in threaded engagement with the other cylindrical element.

CROSS-REFERENCE TO RELATED APPLICATIONS

Priority is claimed to PCT application No. PCT/SE95/01001 filed Sep. 7,1995, based on Swedish patent application No. 9403815-5 filed Nov. 8,1994 and Denmark utility model application No. 94-00346 UM, filed Sep.8, 1994.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND OF THE INVENTION

The present invention relates generally to a device for coupling pipesections whose one end has an outwardly directed bead or a plurality ofprojections positioned along the circumference. The invention isparticularly directed to a device with a clamping band of the type whichpreferably is used for the coupling of pipes of thin metal sheet, ofwhich the front ends have flanges or outwardly directed beads, such asspiral-fold ventilating pipes and grain conveying pipes, or for theclamping of, for instance, end covers on electric motors or the like.Pipe sections, to which the invention is applicable, are shown in, forinstance, Danish Design Registration MR 0508/89.

Prior-art clamping bands of this type are usually fitted with a clampingdevice, which can consist of, for instance, a handle with a wire or leafspring (snap lock), the handle and the spring being directly integratedwith the clamping band by bending or like operation, or attached bymeans of mountings which are mounted on the band by riveting or welding.

There are also prior-art clamping bands whose ends are bentperpendicularly away from the band and formed with through holes, theband being clamped by a screw being passed through the outwardly bentends and a preferably square nut being put on the screw, whereupon thescrew and the nut are clamped, thereby moving the ends of the clampingband together.

These prior-art devices are, however, provided with rather complicatedclamping mechanisms. Usually, the abutment means cooperating with thestraining screw are specially designed and positioned in speciallyconstructed spaces or pockets which are defined by flanges of theclamping band. For instance, the pockets may be formed by the two endportions of the clamping band being rearwardly bent and riveted,soldered or welded to the outer circumference of the clamping band. Thismakes the construction of the clamping device expensive.

Therefore, the object of the invention is to provide a simple andinexpensive coupling device which eliminates the drawbacks inherent inprior-art clamping bands. Moreover, the invention aims at providing acoupling device having a good sealing effect.

BRIEF SUMMARY OF THE INVENTION

According to the invention, these and other objects, which will appearfrom the description below, are now achieved by means of a device forcoupling first and second pipe sections each having an outwardlydirected bead at a respective end thereof, said device comprising: anannular clamping band with two opposite, spaced-apart ends, at which aclamping mechanism is arranged for tightening the band around the endbeads of the pipe sections; the clamping band being of substantiallyU-shaped cross-section with two flanges for safely encompassing the endbeads; each end of the clamping band forming a pocket withcircular-cylindrical cross-section; said clamping mechanism comprisingfirst and second cylinder elements which are each arranged in a separatepocket and have a circular-cylindrical cross-section, the greatestcross-sectional dimension of said cylinder elements being slightlysmaller than the smallest internal cross-sectional dimension of saidpocket; and a straining screw for connecting said cylinder elements; thefirst cylinder element having a transverse threaded hole, whereas thesecond cylinder element has a transverse unthreaded hole; said strainingscrew extending freely through the unthreaded hole, through unthreadedholes in the opposite ends of the clamping band and finally being inthreaded engagement with the threaded hole; characterized in that thefirst and second cylinder elements are arranged freely rotatable abouttheir own axis inside the respective pocket; and that the clamping bandon its inside facing the end beads of the pipe sections has acircumferential seal for abutment against the end beads.

Owing to the cylindrically designed pockets at the ends of the clampingband and the cylindrical elements arranged therein, the clamping band issubjected mainly to tangential forces while being drawn together, sincethe two cylindrical elements have the possibility of turning as the bandis drawn together to a smaller diameter. In prior-art clamping bands ofthe type in which flanges are bent perpendicularly away from the bands,these flanges are, however, subjected to heavy stress during drawingtogether, since they are not perpendicular to the direction of drawingtogether.

The inventive clamping band has the additional advantage that it is easyto manufacture, since no riveting, soldering, welding or other fasteningof the clamping parts is required, and that the used cylindricalelements and the screw can be of standard type and are available on themarket.

The pockets, which are preferably formed in a simple bending operation,can be of, for instance, circular-cylindrical or square cross-section,and the corresponding cylindrical elements can be of square andcircular-cylindrical cross-section, respectively.

The device according to the invention has the advantage in respect ofmanufacturing technique that the two cylindrical elements can be readilyinserted sideways into the respective pockets in the ends of theclamping band. The clamping band is preferably supplied with thecylindrical elements positioned in the pockets and the straining screwinserted through and in engagement with the holes in the cylindricalelements.

According to a preferred embodiment, both the pockets and thecylindrical elements are of circular-cylindrical cross-section. Thisresults in the cylindrical elements having a larger engagement surfacein the pocket such that the clamping force is distributed over a greaterpart of the inside of the pocket.

For preventing leakage in the joint between the pipe sections, theclamping band is, according to a preferred embodiment, fitted with aninternal circumferential seal which preferably is made of rubber andwhich has two cross-sectionally cup-shaped portions for engaging the twobeads of the pipe sections.

BRIEF DESCRIPTION OF THE DRAWING

The invention will now be described in more detail below with referenceto the accompanying drawing which illustrates various embodiments and inwhich:

FIG. 1 shows a pipe coupling with a clamping band according to theinvention seen in the direction of arrows I--I in FIG. 3,

FIG. 2 is a side view of an end of the clamping band in FIG. 1,

FIG. 3 is a side view of part of the clamping band, whose ends areprepared to be clamped, the pipes in the pipe coupling, however, beingexcluded for the sake of clearness,

FIGS. 3a and 3b illustrate two alternative embodiments of pockets andcylindrical elements,

FIG. 4 is a side view, on a smaller scale, of the entire couplingdevice,

FIG. 5 is a view, corresponding to FIG. 1, of an embodiment with aninternal seal on the clamping band, and

FIG. 6 shows the pipe coupling and clamping band of FIG. 1 with theinternal seal of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a coupling device according to the invention, comprising aclamping band 1 being of U-shaped cross-section and having two flanges1a, 1b joined by a bead bridging member which here encompass twoschematically illustrated pipe sections 10, 20 with circumferential endbeads 11 and 21, respectively, which are formed by bending. The endbeads 11 and 21 each include radially outwardly directed surfaces 12 and22 and surfaces 13 and 23 that oppose each other and lie in a planeorthogonal to the axis of the pipe sections when the pipe sections arecoupled in end-to-end relationship. The flanges 1a, 1b diverge slightlyin order to facilitate the mounting of the clamping band 1 on the beads11, 21.

The clamping band 1 shown in FIGS. 1-3 has end portions 2 which are bentto partially circular shape, form pockets and are each provided with anunthreaded hole 3 whose axis is substantially parallel to the tangentline of the clamping band 1 in the position concerned.

As best seen in FIG. 3, there is in one end portion 2 arranged anut-shaped abutment in the form of a short cylindrical element 4 havinga transverse threaded hole 4a. In the other end portion there isarranged a further element, which is also in the shape of a shortcylindrical element 5 but which has a transverse unthreaded hole 5a fora tightening screw 6.

The components and parts 2-6 thus form a simple, but efficient clampingmechanism for displacing the end portions 2 of the clamping band 1relative to each other, whereby the band 1 can be tightened and thedesired clamping around the beads 11, 21 can be achieved.

As shown in FIGS. 3a and 3b, as variants, a cylindrical element ofsquare cross-section can be arranged in a circular-cylindrical pocket,or a circular-cylindrical element can be arranged in a pocket of squarecross-section. To accommodate the tightening screw 6, the end portionsof the clamping band 1 are in this case fork-shaped at the free ends.

According to a preferred embodiment, the clamping band 1 has an internalcircumferential seal 25, as shown in FIGS. 5 and 6, consisting of apolymer, preferably rubber. The surface of the seal 25 facing the beads11, 21 (FIGS. 1 and 6) has two cup-shaped portions 26 for providingreliable abutment against the radially outwardly directed surfaces 12,22 of the beads 11, 21. It will be appreciated that the seal may haveother cross-sectional shapes as long as a satisfactory sealing functionis achieved.

What is claimed is:
 1. A pipe coupling assembly comprising:first andsecond pipe sections of ventilating pipes and grain conveying pipesformed from metal sheet, each pipe section having an outwardly directedend bead at a respective end thereof, each end bead having a radiallyoutwardly directed surface and a surface flush with the respective pipesection end and lying in a plane orthogonal to the axis of the pipesections and opposing the other end bead when the first and second pipesections are coupled in an end-to-end relationship; a coupling devicecomprising:an annular clamping band with two opposite, spaced-apartends, at which a clamping mechanism is arranged for tightening the bandaround the end beads of the pipe sections, the clamping band being ofsubstantially U-shaped cross-section and comprising:an annular beadbridging member having a radially inwardly facing inside surfaceextending linearly across the radially outwardly directed surfaces ofthe end beads when arranged in the end-to-end relationship, and twoflanges extending inwardly from opposite edges of the bead bridgingmember, the bead bridging member and the two flanges arranged forsecurely encompassing the end beads; each respective end of the clampingband having respective first and second pockets each with at leastpartial circular-cylindrical cross-section and having a hole through anadjacent portion of the clamping band end; said clamping mechanismcomprising:first and second cylindrical elements which are each arrangedin said first and second pockets respectively and each having acircular-cylindrical cross-section, a cross-sectional dimension of saidfirst and second cylindrical elements at their greatest being slightlysmaller than an internal cross-sectional dimension of said first andsecond pockets at their smallest, and a tightening screw for connectingsaid cylindrical elements, the first cylindrical element having atransverse hole threaded for said tightening screw, the secondcylindrical element having a transverse hole permitting free movement ofsaid tightening screw; said tightening screw extending freely throughthe hole of said second cylindrical element, through the holes in theends of the clamping band and being in threaded engagement with thethreaded hole of said first cylindrical element; each of said first andsecond cylindrical elements being freely rotatable inside the respectivefirst and second pockets about a cylindrical axis thereof; and acircumferential seal disposed on the inside surface of the bead bridgingmember of the clamping band to abut against said radially outwardlydirected surfaces of the end beads to exert a radially inwardly directedpressure on the radially outwardly directed surfaces of the end beads toform a sealing surface thereagainst, the seal configured to overlie theend beads and having a configuration complementary to the radiallyoutwardly directed surfaces of the end beads, the seal furtherconfigured to fill a space between the radially outwardly directedsurfaces of the end beads and the inside surface of the bead bridgingmember without extending into a space between the opposed surfaces ofthe end beads when coupled in the end-to-end relationship.
 2. Theassembly as claimed in claim 1, wherein a surface of said seal facingthe end beads has two cup-shaped portions for abutment against therespective end beads.
 3. The assembly as claimed in claim 1, wherein theseal consists of an elastic polymer.
 4. The assembly of claim 3 whereinsaid polymer is rubber.